Copyboard having automatic latch releasing means

ABSTRACT

In graphic arts camera apparatus, a copyboard mounted on a frame for tiltable movement and having a cover section hinged to a base section and releasable latch for fastening the sections together is characterized by a latch actuator for automatically releasing the latch to permit separation of the hinged sections whenever the copyboard tilts from a vertical exposing position to a horizontal loading and unloading position. A catch mechanism prevents inadvertent release of the latch when the copyboard is vertically disposed, and the latch is biased toward a latched position to facilitate fastening the sections subsequent to loading the copyboard.

United States Patent 2,758,503 8/1956 Luffmanetal. 3,089,385 5/1963Wanielista Primary Examiner-Samuel S. Matthews AssistantExaminer-Russell E. Adams, Jr. Attorney-Hill, Sherman, Meroni, Gross &Simpson ABSTRACT: In graphic arts camera apparatus, a copyboard mountedon a frame for tiltable movement and having a cover section hinged to abase section and releasable latch for fastening the sections together ischaracterized by a latch actuator for automatically releasing the latchto permit separation of the hinged sections whenever the copyboard tiltsfrom a vertical exposing position to a horizontal loading and unloadingposition. A catch mechanism prevents inadvertent release of the latchwhen the copyboard is vertically disposed, and the latch is biasedtoward a latched position to facilitate fastening the sectionssubsequent to loading the copyboard.

ill 0 |o :l ll I0 ill'" PATENTED [EC] 41971 SHEET 1 BF 2 m w a 4 w m m f5 M x 5 J M a 67 24 86 J 5 wmg 52% W a w x a a m a m xzmziam 5 -A z acan 3 If?! i PATENTED 05m 4197! SHEET 2 [IF 2 BACKGROUND OF'THEINVENTION 1. Field of the Invention This invention relates to acopyboard construction for graphic arts camera apparatus, and moreparticularly to a copyboard mechanism having means automaticallyactuating releasable latching means whenever the copyboard moves to apredetermined loading position offset from an exposing position forfacilitating loading and unloadingthe copyboard.

2. Description of the Prior Art Process cameras for 7 use H in graphicarts, printing, photofabrication and similar applications generally havea base slidably supporting a camera and a frame having a copyboardmounted thereon for. tilt'able movement selectively between a verticalexposing position and a horizontal loading and unloadingpositio'n.Material to be exposed is positioned on a support surface or a copyboardbase section and held in position by a cover section hinged to the baseand having a transparent glass window.

Improved productivity of process cameras requires rapid loading andunloading of the copyboard. Copyboards heretofore available have been asource of lost time because of the various manual movements required tounlatch the cover sec tion, position the materialandsecurely fasten thecover to the base. I J 1 3 Further, inadvertent unlatching of the coverwhile the copyboard is disposed in a position offset from the horizontalposition may result in breakage'of the glass window or possibly otherdamage. f

SUMMARY OF THE INVENTION Inaccordance with the present invention. acopyboard'for a graphic arts camera or light-exposure system is mountedon a frame for tiltable movement between a vertical exposing positionand a horizontalloading and unloading positionan'd has 'means I attachedto the frame for automatically releasing latching means fastening ahinged cover section to a base section as the copyboard approaches thehorizontal position. A portion of the latch releasing means restrainsthe copyboard base and springs in the base, w'hichpush material to beexposed against a glass window, urge the unlatched cover away from theclamped base, thereby to automatically open the copyboard withoutrequiring separate manual operations. The latching means generallycomprise a latch bar mounted in the base for reciprocalmovement betweenlatched and unlatched positions, complemental latch portions attached tothe timer and forming recesses for receiving detents carried by thelatch bar, and biasing means urging the latch bar toward the latchposition wherein the detents are received in the recesses. I

As the cover is pivoted toward the base for clamping a properlypositioned piece of copy or other material to be exposed. cammingsurfaces on the cover latch portions move the latch bar toward theunlatched position for enabling the biasing means to urge the detents'into the recesses, thereby automatically latching the cover withoutrequiring separate manual operations. A handle portion extendsexteriorly of the copyboard and has an end portion attached to the latchbar to permit manual unlatching while the copyboard is horizontallydisposed, thereby to enable correcting alignment of the piece of copy,if necessary.

After loading, the clamping portion of the latch releasing means istilted clear of the base to free the copyboard for tilting movementtoward the vertical exposing position.

In order to prevent inadvertent unlatehing while the copyboard isvertically disposed, as the copyboard tilts from the horizontal positiona catch mechanism engages the latch bar for restraining reciprocalmovement thereof. An abutment on the frame moves the catch clear of thelatch bar as the copyboard approaches the horizontal to permit releaseof the latch by the automatic latch releasing means.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side elevational viewvof agraphic arts camera including a copyboard constructed in accordance withthe principles of the present invention and illustrating the copyboardin a vertical, exposing position;

FIG. 2 is a perspective view of the copyboard shown in FIG. I andillustrating the copyboard in a horizontal loading and unloadingposition;

FIG. 3 is a transverse sectional view taken along an edge of thecopyboard and illustrating latching means and automatic latch releasingmeans embodying theprinciples of the present invention; I t p I FIG. 4is a fragmentary sectional 'view taken substantially along line IV-IV ofFIG. 3:

FIG. 5 is a fragmentary sectional view taken substantially along lineV-V of FIG. 3; and v FIG. 6 is a sectional view talten substantiallyalong line VI- VI'ofFlG. 3. Y

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT I Referring to thedrawings, a copyboard mechanism 10, constructed in accordance with theprinciples of the present invention, is journaled between'a pair ofupright framing members I1, 11 which in turn are slidably supported onrails as at I2 forming a bedfor a graphic arts camera. A camera l3-issupported on the camera bed 12 at an end thereof opposite the copyboardl0 and has'a front lens case 14 carried onthe rails 12 for slidablemovement toward and away from the copyboard to focus the camera Thecamera 13 includes a bellows I5 and a vacuum film holder 15c operativelyconnected to a vacuum source V by a conduit C. It -will be understoodthatydepending on the size of the camera, the vacuumfilm holder 15a maybe located in a dark room while'the copyboard I0'is located in agallery. The camera. construction also includes illumination meanssuchas the lights I. for suitably illuminating the copyboard 10'. I I IJ I The copyboard I0 includes 'a cover or front section l6 hingedlyconnected for pivotal movement along an edge as at 17 to a base or backsection I8. The base or back section I8 provides a support surface whichmay include a resiliently mounted pad 18a against which a piece of copy1812 is disposed, and the cover 16 has a transparent glass window 18cabutting the piece of copy, thereby to clamp the piece of copy betweenthe copyboardsections. I

The upright framing members II comprise box-shaped channel members eachhaving a pair of parallel sidewalls as at I9 characterized by alignedapertures 21 forreceiving one end portion of a pair of 'shafts'as at 22;The other end of the shafts 22 are journaled into a pair of bearingblocks as at 23attached to opposite end edge portions of the base orback section 18 for pivotally mounting the copyboard 10 between the pairof framing members 11, II for tiltable movement about a horizontal axisextending perpendicularly to an axis of the hinged connection I7. Thecopyboard 10 may be tilted selectively between a vertical, exposingposition, as shown in FIG. 1, and a horizontal loading and unloadingposition, as illustrated in FIG. 2.

To assist an operator in opening and closing the hinged cover I6 and tocontrol positioning of the cover, counterbalancing spring means as'at 24maybe pivotally mounted at opposite sides of the sections 16 and 18, asillustrated in FIG.

Latching means fastening the cover section 16 to the base section 18 forclamping the piece of copy 18c between the pad and the window 18ccomprise a latch bar 26 mounted on the base section for reciprocationtherealong. The latch bar 26 has detents as at 27 for releasablyengaging recesses as at 28 formed in latch fingers 29 attached to thecover section.

The latch bar 26 is an elongated strip-form member disposed along a wall31 of the base I8. A plurality of nut and bolt assemblies as at 32 passthrough spaced-apart apertures formed in the wall 3] and are received inelongated attachment apertures as at 33 formed in the latch bar 26 topermit longitudinally directed, reciprocal movement of the latch barrelative to the base section 18 selectively between a latched position,as illustrated in H0. 3, and an unlatched position wherein the latch baris shifted to the left of the position shown in FIG. 3.

Biasing means urge the latch bar 26 toward the latched posi-' tion andcomprise a tension spring 34 having one end portion as at 36 secured toa sidewall 37 of the base member 18 by a screw fastener 38 and anotherend 39 anchored to the latch bar by means of an upstanding tab 41. Atleast one of the attachment slots 33 has an end wall as at 42 forming anabutment surface engaging the associated nut and bolt assembly 32 forlimiting movement of the latch bar toward the latched position under theinfluence of the tension spring 34.

The detents 27 include Z-shaped members having an upper leg 43 spacedfrom and extending parallel with the latch bar 26 and aligned with therecesses 28 formed in latch fingers 29 when the cover is firmly closed.The latch fingers 29 are Z- shaped in configuration and have a planarportion 44 apertured for receiving fastening means such as rivets as at46 for attaching the fingers to a cover end wall 47. A portion 48 ofeach of the latch fingers 29, is spaced from and extends parallel to theplanar portion 44. A recess 28 is formed in each respective latch finger29 for receiving a detent 27. Each portion 48 has an angular cammingsurface as at 49 disposed to incline downwardly away from the detents27. Thus, when the cover section 16 is pivoted about the hingedconnection 17 toward the base 18, a lowermost end of the camming surface49 will engage the leading edge 51 of a corresponding detent 27. Furthermovement of the cover toward the closed position will cam the latch bar26 against the bias of the tension spring 34 and toward the unlatchedposition, thereby enabling the detents 27 to be received in the recesses28.

In accordance with the principles of the present invention, automaticlatch releasing means are provided which are shown generally at 52.

The automatic latch releasing means 52 comprise a plate member 53 havinga generally upwardly extending actuating portion or finger 54characterized by an angular camming surface 56. The baseplate wall 31has an elongated clearance aperture 57 formed therein for receiving theactuating portion 54 as the copyboard approaches the horizontalposition, and the latch bar 26 has an elongated aperture 58 in alignmentwith the clearance aperture 57 and characterized by an end wall 59forming an abutment surface disposed for engagement with the cammingsurface 56.

As the copyboard l approaches the horizontal loading and unloadingposition, the abutment surface 59 engages an upper end portion of thecamming surface 56 formed on the plate 53. Further movement toward thehorizontal position causes the abutment surface to ride along the camsurface 56 and thus shifts the latch bar 26 against the bias of thetension spring 34 and toward the unlatched position for unlatching thecover 16. The camming surface 56 is sized in a direction parallel to thelatch bar movement so that the latch bar is shifted a greater distancethan the overlap between the detents 27 and the recesses 28 to unlatchthe copyboard sections 16 and 18.

With the latch bar 26 in the unlatched position, compression springs 60,which resiliently support the pad 180 urge the cover 16 away from thebase 18 to slightly separate the respective copyboard sections. Aplurality of the springs 60 are disposed around the base 18, and each ofthe springs encircles a machine screw 60a and has opposite end portionsoperatively engaging the pad and the base. Each of the machine screws60a passes through a clearance aperture 60b in the base 18 and engagesinto the pad 18a, thereby to permit limited movement of the pad relativeto the base.

In order to lock the base section 18 into the horizontal position, theactuating portion or finger 54 has a recess 61 for receiving aperipheral edge portion 62 of the aperture 58. Thus, when the basesection 18 is aligned in the horizontal position, the peripheral edgeportion -62 is in alignment with the recess 61 and will be urged by thetension spring into locking engagement therewith. A closing of the cover16 will cause a movement of the latch bar 26, as a result of engagementbetween the camming surfaces 49 and the detents 27, less than the amountnecessary to produce disengagement between the latch bar 26 and thefinger 54.

It is also contemplated by the present invention to tiltably mount thelatch releasing plate 53 and. to provide means for tilting the plate 53to a release position. The latch releasing plate 53 is verticallydisposed along a support block 63 which in turn is secured to theframing member 11, disposed adjacent the end of the copyboard mountingthe latch bar 26, by means of bolts 64. A pin 66 has one end portionpress fit into an aperture 67 formed in the support block 63 and anotherend portion loosely received in a clearance aperture 68 formed in theplate 53. The axis of the pin 66 is disposed directly beneath thecamming surface 56. A snapring 69 or other suitable fastening meansengages the pin 66 and overlies peripheral edges of the clearanceaperture 68, thereby to pivotally mount the plate 53 on the pin fortiltable movement selectively between an upright position, wherein theabutment surface 59 will engage the camming surface 56 for unlatchingthe latch means, and a release position, wherein the recess 61 iswithdrawn from engagement with the peripheral locking edge 62.

In order to selectively tilt the latch releasing plate 53 toward therelease position, an eccentric cylindrical surface 71 is formed on acontrol shaft 72 and is received in a vertically elongated slot 73formed in the latch releasing plate 53 and laterally offset from theclearance aperture 68. The control shaft 72 is joumaled in alignedapertures 76 and 77 respectively formed in the support block 63 and theframing member sidewalls 21, and an actuating handle 79 secured at anend of the control shaft projecting outwardly of the framing member 11permits manual operation of the release mechanism, thereby to enablemovement of the copyboard from the loading position to the exposingposition. The axis of the control shaft 72 extends at right angles to aplane containing the plate 53 and parallel with the axis of the pivotpin 66 and is laterally and upwardly offset therefrom, thereby to pivotthe latch release plate 53 in a clockwise direction whenever the controlhandle 79 is manually pivoted in a counterclockwise direction. Further,the mechanical advantage provided by the eccentric surface 71 preventsrotational movement of the plate 53 about the pin 66 as the latch bar 26engages the camming surface 56 to unlatch the cover 16.

A torsion spring 81 wrapped around the innermost end 82 of the controlshaft 72 and anchored against a pin 83 press fit into the support block63 biases the control shaft toward a clockwise direction and thus biasesthe latch releasing plate 53 toward the upright position. The pin 83along with another pin 84 angularly offset from the first pin formabutments engaged by a pin 86 extending laterally from the control shaft72, thereby to provide stops limiting pivotal movement of the controlshaft.

In order to permit unlatching while the copyboard 10 is disposed in thehorizontal loading and unloading position, for example to realign aworkpiece subsequent to initially closing the cover, a handle 91 has oneend portion as at 92 pivotally connected to the sidewall 37 of the basesection 18 by means of a bolt and nut assembly 93 and is characterizedby a rod 94 extending from the other handle end 96 through a clearanceopening 97. The rod 94 is attached by welding or other suitable means tothe latch bar 26, and thus, an inwardly directed force pivots the handle91 to slide the latch bar 26 toward the unlatching position. To permitunlatching of the bar 26 while preventing release of the base 18 fromthe horizontal loading position, the detents 27 are received in therecesses 28 a distance less than the overlap between the peripheral edge62 of the aperture 58 and the actuating finger 54. A shoulder 98 on thehandle end 96 forms an abutment to limit movement of the latch bar 26 bythe handle 91 to a distance less than the overlap between the edge 62and the finger 54 but great enough to shift the detents 27 clear of therecesses 28. Thus, the latch bar 26 may be manually shifted to theunlatched position without releasing the base 18 from the loadingposition.

It is also contemplated by the present invention to provide a catchmechanism for engaging the latch bar 26 as the copyboard tilts upwardlyfrom the horizontal position to restrain movement of the latch bar forpreventing inadvertent unlatching of the cover, which may cause breakageof the glass window 180 and possibly other damage. The catch mechanismincludes a catch member 101 having one end portion journaled on thepivot shaft 22 and an opposite end portion formed with an offset portion102. An elongated slot 103 formed in the latch bar 26 receives theoffset portion 102 on the catch 101 and is sized relative to the offsetportion for restraining movement of the latch bar 26 toward theunlatching position whenever the catch is properly engaged therein. Atorsion spring 104 embraces the pivot shaft 22 and has an end 105engaging the catch for biasing the same downwardly toward the latch bar26.

Release means for the catch mechanism include an upstanding abutment 106adjustably threadedly attached to a stud 107 projecting upwardly fromthe support block 63. The abutment 106 is disposed relative to the catchreceiving slot 103 and the clearance slot 57 to pass therethrough andengage a lower edge of the catch offset portion 102 as the copyboard 10approaches the horizontal position, thereby pivoting the catch member101 against the bias of the torsion spring 104 and out of engagementwith the slot 103. Also, as the copyboard 110 is upwardly tilted aboutthe pivot shaft 22 toward the vertical position the slot 103 moves awayfrom the abutment 106, thereby enabling the catch 101 to pivot under theinfluence of the torsion spring 104 to a position wherein the offsetportion 102 engages the slot 103.

An enlarged portion 108 on the abutment post 106 engages peripheral edgeportions of the clearance slot 57 formed in the wall 31 of the basesection 18 for providing an adjustable stop to determine the horizontalloading and unloading position of the copyboard l0.

Although those versed in the art might suggest various minormodifications. it should be understood that I wish to embody within thescope of the patent warranted hereon all such modifications asreasonably and properly come within the scope of my contribution to theart.

I claim as my invention:

1. ln a copyboard mechanism, for use in a light-exposure system.including a base section and a cover section hingedly connected to thebase section and support means having one of said sections journaledthereon for tiltable movement between a vertical exposing position and ahorizontal loading and unloading position, the improvement comprising:

releasable latch means fastening the cover section to the base sectionfor clamping work pieces therebetween,

said latch means comprising a latch bar mounted on the base section forreciprocal movement selectively between a latched position and anunlatched position,

means forming detents attached to one of said latch bar and the coversection, and

means forming latch portions attached to the other one of said latch barand the cover section and having recesses formed therein for receivingsaid detents;

automatic latch releasing means having a camming surface engaging aportion of said latch bar for shifting the same toward the unlatchedposition as the copyboard approaches the horizontal loading andunloading position,

said latch releasing means comprising a plate member formed with -anupstanding portion having said camming surface formed thereon anddisposed to be engaged by a portion of said latch bar as the copyboardsections approach the horizontal position.

2. A copyboard as defined in claim 1 and further characterized by:

said latch bar having a slot formed therein and disposed to receive saidupstanding portion on said latch releasing plate member, said slothaving an end wall engaging said camming sur- 5 face as the copyboardsections approach the horizontal position; and biasing meansinterconnecting said latch bar and a portion of said base section andnormally urging said latch bar toward the latched position. 3. Acopyboard as defined in claim 2 and further characterized by:

said latch releasing means including means forming a recess in saidplate member disposed to receive a peripheral edge of said slot adjacentsaid one end wall whenever said base section tilts into the horizontalloading and unloading position, whereby said biasing means urges saidperipheral edge of said slot into said plate recess to lock said basesection into the horizontal position.

4. A copyboard as defined in claim 5 and further characterized by:

said latch releasing means having means supporting said plate fortiltable movement selectively between a first position wherein saidperipheral edge lockingly engages said plate recess whenever said latchbar is in the latched position and a second position wherein said platerecess is withdrawn from locking engagement with said peripheral edgeportion;

means for tilting said plate member selectively between the first andsecond positions thereof.

5. A copyboard as defined in claim 4 and further characterized by: 1

said means for tilting said plate member comprising 35 a control shaftjournaled in said support means;

a cylindrical surface eccentrically formed on said shaft; an elongatedslot formed in said plate and receiving said eccentrically formedcylindrical surface,

whereby rotation of said control shaft in one angular direction tiltssaid plate member about the tilting axis from the first position to thesecond position for enabling said base section to be tilted from thehorizontal position.

6. In a copyboard, for use in a light-exposure system, including a basesection and a cover section hingedly connected to the base section andsupport means having one of the sections journaled thereon for tiltablemovement between a vertical exposing position and a horizontal loadingand unloading position, the improvement comprising:

releasable latch means fastening the cover section to the base sectionfor clamping work pieces therebetween; abutment means attached to thesupport means and forming a horizontal stop surface engageable with thebase section whenever the copyboard sections are pivoted to thehorizontal loading and unloading position;

automatic latch releasing means operating on said releasable latch meansas the copyboard sections approach the horizontal position for releasingsaid latch to permit separation of the sections; and

said latch releasing means including locking means for retaining thebase section in abutting engagement with said stop surface and beingreleasable to permit pivoting said sections toward the verticalposition.

7. A copyboard as defined in claim 1 and further characterized by:

a catch mechanism having a catch member mounted adjacent saidreciprocally movable latch bar for movement selectively toward and awayfrom said bar;

means forming an aperture in said latch bar for receiving a portion ofsaid catch member;

said aperture sized relative to said catch portion for restrainingreciprocal movement of said latch bar whenever said catch is engaged insaid aperture;

biasing means normally urging said catch member towards said latch barand into engagement with said latch bar aperture; and

means forming an upstanding post attached to said support means anddisposed to engage said catch member for moving the same against saidbiasing means and away from said latch bar as said copyboard approachesthe horizontal position.

8. A copyboard as defined in claim I and further characterized by:

means forming a handle portion attached to said latch bar and extendingexteriorly of said copyboard;

mounting means supporting said handle for reciprocal movement indirections parallel with reciprocal movement of said latch bar,

thereby enabling manual movement of said latch bar between the latchedand unlatched positions.

9. In a copyboard mechanism, for use in a light-exposure system,including a base section and a cover section hingedly connected to thebase section and support means having one of said sections joumaledthereon for tiltable movement between a vertical exposing position and ahorizontal loading and unloading position, the improvement comprising:

releasable latch means fastening the cover section to the base sectionfor clamping work pieces therebetween and including a latch bar mountedon the base section for reciprocal movement selectively between alatched position and an unlatched position;

automatic latch releasing means operating on said latch bar as thecopyboard sections approach the horizontal position for releasing saidlatch means to enable separation of the copyboard sections;

said latch releasing means comprising means lockingly engaging saidlatch bar after the release of said latch means for retaining the basesection in a horizontal loading and unloading position.

10. A copyboard mechanism as defined in claim 9, further characterizedby:

biasing means normally urging said latch bar towards the latch position;and

said automatic latch releasing means comprising a plate member having acamming surface formed thereon and disposed to be engaged by a portionof said latch bar as the copyboard sections approach the horizontalposition;

said camming surface being configured to move said latch bar againstsaid biasing means for releasing said latch means; and

said camming surface. having a recess formed therein and disposed toreceive a portion of said latch bar in locking engagement therewithwhenever the base section is in the horizontal loading and unloadingposition.

11. A copyboard as defined in claim 10 and further characterized by:

means forming detents attached to one of said latch bar and the hingedcover section;

means forming latch portions attached to the other one of said latch barand the hinged cover section and having latching recesses formed thereinfor receiving said detents; and

said recess formed in said camming surface being sized relative to saiddetents and said latching recesses to permit movement of said latch baragainst said biasing means a distance sufficient to unlatch the coversection without moving said latch bar out of locking engagement withsaid recess formed in said camming surface.

12. A copyboard as defined in claim 10 and further characterized by:

said latch releasing means including means supporting said plate fortiltable movement selectively between a first position wherein saidrecess in said camming surface is disposed for locking engagement withsaid latch bar and a second position wherein said recess is withdrawnfrom locking engagement with said latch bar; and

means for tilting said plate member selectively between the first andsecond positions thereof.

i l '0 i t

1. In a copyboard mechanism, for use in a light-exposure system,including a base section and a cover section hingedly connected to thebase section and support means having one of said sections journaledthereon for tiltable movement between a vertical exposing position and ahorizontal loading and unloading position, the improvement comprising:releasable latch means fastening the cover section to the base sectionfor clamping work pieces therebetween, said latch means comprising alatch bar mounted on the base section for reciprocal movementselectively between a latched position and an unlatched position, meansforming detents attached to one of said latch bar and the cover section,and means forming latch portions attached to the other one of said latchbar and the cover section and having recesses formed therein forreceiving said detents; automatic latch releasing means having a cammingsurface engaging a portion of said latch bar for shifting the sametoward the unlatched position as the copyboard approaches the horizontalloading and unloading position, said latch releasing means comprising aplate member formed with an upstanding portion having said cammingsurface formed thereon and disposed to be engaged by a portion of saidlatch bar as the copyboard sections approach the horizontal position. 2.A copyboard as defined in claim 1 and further characterized by: saidlatch bar having a slot formed therein and disposed to receive saidupstanding portion on said latch releasing plate member, said slothaving an end wall engaging said camming surface as the copyboardsections approach the horizontal position; and biasing meansinterconnecting said latch bar and a portion of said base section andnormally urging said latch bar toward the latched position.
 3. Acopyboard as defined in claim 2 and further characterized by: said latchreleasing means including means forming a recess in said plate memberdisposed to receive a peripheral edge of said slot adjacent said one endwall whenever said base section tilts into the horizontal loading andunloading position, whereby said biasing means urges said peripheraledge of said slot into said plate recess to lock said base section intothe horizontal position.
 4. A copyboard as defined in claim 3 andfurther characterized by: said latch releasing means having meanssupporting said plate for tiltable movement selectively between a firstposition wherein said peripheral edge lockingly engages said platerecess whenever said latch bar is in the latched position and a secondposition wherein said plate recess is withdrawn from locking engagementwith said peripheral edge portion; means for tilting said plate memberselectively between the first and second positions thereof.
 5. Acopyboard as defined in claim 4 and further characterized by: said meansfor tilting said plate member comprising a control shaft journaled insaid support means; a cylindrical surface eccentrically formed on saidshaft; an elongated slot formed in said plate and receiving saideccentrically formed cylindrical surface, whereby rotation of saidcontrol shaft in one angular direction tilts said plate member about thetilting axis from the first position to the second position for enablingsaid base section to be tilted from the horizontal position.
 6. In acopyboard, for use in a light-exposure system, including a base sectionand a cover section hingedly connected to the base section and supportmeans having one of the sections journaled thereon for tiltable movementbetween a vertical exposing position and a horizontal loading andunloading position, the improvement comprising: releasable latch meansfastening the cover section to the base section for clamping work piecestherebetween; abutment means attached to the support means and forming ahorizontal stop surface engageable with the base section whenever thecopyboard sections aRe pivoted to the horizontal loading and unloadingposition; automatic latch releasing means operating on said releasablelatch means as the copyboard sections approach the horizontal positionfor releasing said latch to permit separation of the sections; and saidlatch releasing means including locking means for retaining the basesection in abutting engagement with said stop surface and beingreleasable to permit pivoting said sections toward the verticalposition.
 7. A copyboard as defined in claim 1 and further characterizedby: a catch mechanism having a catch member mounted adjacent saidreciprocally movable latch bar for movement selectively toward and awayfrom said bar; means forming an aperture in said latch bar for receivinga portion of said catch member; said aperture sized relative to saidcatch portion for restraining reciprocal movement of said latch barwhenever said catch is engaged in said aperture; biasing means normallyurging said catch member towards said latch bar and into engagement withsaid latch bar aperture; and means forming an upstanding post attachedto said support means and disposed to engage said catch member formoving the same against said biasing means and away from said latch baras said copyboard approaches the horizontal position.
 8. A copyboard asdefined in claim 1 and further characterized by: means forming a handleportion attached to said latch bar and extending exteriorly of saidcopyboard; mounting means supporting said handle for reciprocal movementin directions parallel with reciprocal movement of said latch bar,thereby enabling manual movement of said latch bar between the latchedand unlatched positions.
 9. In a copyboard mechanism, for use in alight-exposure system, including a base section and a cover sectionhingedly connected to the base section and support means having one ofsaid sections journaled thereon for tiltable movement between a verticalexposing position and a horizontal loading and unloading position, theimprovement comprising: releasable latch means fastening the coversection to the base section for clamping work pieces therebetween andincluding a latch bar mounted on the base section for reciprocalmovement selectively between a latched position and an unlatchedposition; automatic latch releasing means operating on said latch bar asthe copyboard sections approach the horizontal position for releasingsaid latch means to enable separation of the copyboard sections; saidlatch releasing means comprising means lockingly engaging said latch barafter the release of said latch means for retaining the base section ina horizontal loading and unloading position.
 10. A copyboard mechanismas defined in claim 9, further characterized by: biasing means normallyurging said latch bar towards the latch position; and said automaticlatch releasing means comprising a plate member having a camming surfaceformed thereon and disposed to be engaged by a portion of said latch baras the copyboard sections approach the horizontal position; said cammingsurface being configured to move said latch bar against said biasingmeans for releasing said latch means; and said camming surface having arecess formed therein and disposed to receive a portion of said latchbar in locking engagement therewith whenever the base section is in thehorizontal loading and unloading position.
 11. A copyboard as defined inclaim 10 and further characterized by: means forming detents attached toone of said latch bar and the hinged cover section; means forming latchportions attached to the other one of said latch bar and the hingedcover section and having latching recesses formed therein for receivingsaid detents; and said recess formed in said camming surface being sizedrelative to said detents and said latching recesses to permit movementof said latch bar against said biasing means a distance sufficient tounlatch the Cover section without moving said latch bar out of lockingengagement with said recess formed in said camming surface.
 12. Acopyboard as defined in claim 10 and further characterized by: saidlatch releasing means including means supporting said plate for tiltablemovement selectively between a first position wherein said recess insaid camming surface is disposed for locking engagement with said latchbar and a second position wherein said recess is withdrawn from lockingengagement with said latch bar; and means for tilting said plate memberselectively between the first and second positions thereof.